Plastic Clad Silica Fiber Research Articles

Competition between photobleaching and fluorescence increase of photosensitizing porphyrins and tetrasulphonated chloro-aluminiumphthalocyanine

The time-dependent fluorescence changes of photosensitizing porphyrins and tetrasulphonated chloroaluminiumphthalocyanine (AlClSPc) were measured at different intracellular sites using video-enhanced microscopy and image processing. To obtain variations in intracellular fluorescence intensity, different radiant exposures of a Kr + laser-pumped dye laser were delivered via a 600 μm plastic-clad silica fibre connected to the microscope During irradiation, competition between photobleaching and fluorescence increase of the different dyes was observed. The porphyrins normally showed photobleaching, which was dependent on the sensitizer and its specific accumulation within the cell. Photobleaching was less pronounced for hydrophilic uroporphyrin than for more hydrophobic dyes. In contrast with an almost exponential decrease in porphyrin fluorescence with increasing light dose, the fluorescence intensity of AlClSPc significantly increased at the beginning of irradiation, and could be correlated with intracellular deaggregation.

Polymeric optical mixing rod coupler

Optical mixing rod couplers have been fabricated using extruded plastic tubing filled with optically transparent casting resins to form a waveguide-type mixing region. Asymmetric (1*19) splitter/combiners with plastic fiber and plastic-clad silica fiber pigtails have been made with efficiencies greater than 60% and power uniformities within 1-dB standard deviation. Tested as a combiner, the coupler had an average loss of -1.6 dB with a standard deviation of 0.71 dB. Tested as a splitter, it had an average loss of -14.9 dB with a standard deviation of 0.9 dB, and the excess loss was -2.0 dB. The results suggest that the coupler would be useful in a variety of short-distance optical interconnection applications where multimode step-index fiber is appropriate. It may also offer a higher yield than some competing, more complex techniques.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

The Use of Optical Fiber in Safety-System Design

This paper summarizes the design, installation, and performance of an optical-fiber safety system installed for testing purposes on a production platform in the Gulf of Mexico. This system was installed on a chemelectric treater to monitor five end devices and to determine the feasibility of using fiber optics rather than pneumatics or an electrical system in a harsh environment. Included with a performance summary is a brief history of optical fiber and the potential for these types of safety systems in oilfield applications.

Measurements Of Lateral Offset Power Losses In Step-Index Optical Fibers Scanning Point Sources

We report the results of an experimental study of optical power losses due to lateral offset of the input aperture of a step-index optical fiber used to scan a point source. Data were taken with hard-clad silica and plastic-clad silica fibers having core diameters ranging from 200 to 1000 µm. These results will be useful in establishing alignment criteria for the optical components used in our laser-based remote thermometry research program.

Thermooptic coupler for multimode optical fibers

The detailed theory is presented together with design considerations and recent experimental results for an electronically controllable directional coupler for multimode optical fibers. The device, based on plastic-clad silica fiber, is of exceptionally simple construction and compact size and is highly reliable. A theoretical model of the coupler is described and compared with actual device performance. The coupling can be varied from -4 to -28 dB with an excess loss of <0.2 dB over the entire coupling range, in agreement with theory. Improvements in the present device design are also discussed.

Acceptance-angle measurement of multimode fibers: a comparison of techniques

A number of techniques for measuring multimode fiber acceptance angle are described, and the general requirements and problems particular to each technique are discussed. An experimental comparison is presented of a fiber acceptance-angle technique and a fiber radiation-angle technique. Results are presented on quasi-step index and also plastic-clad silica fibers. It is concluded that the radiation-angle technique offers simplicity of operation with unambiguous results and may, therefore, be a suitable standard method for testing optical fibers.

Libido using Eros: half-duplex optical link

A half-duplex optical link Libido (Liaison bidirectionnelle optique) has been realised using the optimised semiconductor optical transceiver Eros (Emitter-receiver for optical systems). The digital transmission has a bit rate of 10 Mb/s with a biphase code using a step-index plastic-clad silica fibre. The characteristics of the component and the link are presented.

Signal-level dependence in the recovery rate of irradiated plastic-clad silica fibre

The optical recovery of a plastic-clad silica fibre after gamma irradiation was monitored at a wavelength of 850 nm. The recovery rate over the measured range of 10 s to &gt; 1 h was found to be strongly dependent on the signal power passing through the fibre.

Effect of temperature on optical fiber transmission

Results are presented concerning the effects of temperature on the transmission properties of various optical fibers including a silicone plastic clad, an acrylic plastic clad, and CVD step-index fibers both with and without polyurethane jackets. Results are presented for the normalized transmitted power vs temperature, the index of refraction vs temperature, and induced attenuation coefficients vs temperature. The data show that the intrinsic transmission of a CVD fiber is independent of temperature over the -110 to +150 C range. Plastic clad fused silica fibers are subject to transmission losses at lower temperatures due to changes in the optical index of the cladding polymer. Acrylic-clad and plastic-clad silica fibers also show transmission losses at lower temperatures, but to lesser extents.

Contamination of furnace-drawn silica fibers

Contamination originating in an electric resistance furnace was found to increase substantially the losses of unclad and plastic-clad silica fibers. In contrast, the losses of doped silica fibers with sufficient cladding thickness were unaffected by impure drawing conditions. Operating the furnace without muffle tube and protecting the preform with a pure, inert gas injected via a counter-flow resulted in practically contamination-free operation and unclad-fiber losses as low as 3 dB/km. The removal of the muffle tube significantly simplified the furnace operation and reduced the cycling time from many hours to a few minutes.

Transient Radiation Effects in Low-Loss Optical Waveguides

Radiation-induced effects in low loss optical waveguides have been studied to determine parameters affecting the use of these materials in plasma diagnostic instrumentation operating in severe radiation environments. Radiation-induced luminescence of fibers was shown to result from the Cerenkov process occurring within the fibers. Both spectral data and angular dependence of luminescence were used to verify the Cerenkov effect. Absolute magnitude of luminescence data were obtained. Different fiber types were shown to exhibit comparable luminescence output. Radiation-induced absorption was measured immediately following a 40 ns radiation pulse at wavelengths of 600 nm and 800 nm. Saturation effects in absorption were observed as well as changes in fiber recovery vs time as a function of radiation dose. Step- and graded-index profile fibers were shown to exhibit comparable absorption. Fibers tested included plastic clad silica fibers, as well as graded- and step-index germanium-doped and boron-doped fibers. Plastic clad silica fibers exhibited much less radiation-induced absorption than any other fiber type. The data presented allow optical fiber data links to be designed for use in severe radiation environments where data transmission is required during, or shortly after, the radiation pulse.